I am a Luffyboi too.
I am not a blind wanker who justifies everything related to Luffy though
If we want explanation or a way out we can always nitpick:
- Luffy struggled against Hody until the timelimit bubble crisis purely due to plot restriction, since he has G4 already
- Luffy struggled against Doflamingo until his G4 over purely due to plot restriction, he let the citizens throw him and interview him around instead of finishing up with Kong Gatling or KKG
- Luffy hadnt use internal destruction CoA explicitly which he used to break the cuff, to destroy Kaidou's organs from the inside, until now.
- Rayleigh suddenly had amnesia and didnt inform Luffy about Roger being able to do CoC Coating, despite CoC being the technique which Luffy is specialized in, or despite AdvCoC is a tech can only be used by the very strongest ones.
Those points can support that Luffy always held back or, if we want some realistic depiction, saved his overall strength in the previous team battles (all-out reaction, all-out speed, etc) until his competence in AdvCoC increased.